1. Field of the Invention
The present invention relates to a highly smooth fiber having hydrophilic groups. More specifically, the present invention relates to a highly smooth fiber having an excellent processability in terms of dispersion and fiber opening using air flow or a carding machine, produced by depositing a specific fiber treatment agent, thereby providing anti-static properties, high smoothness, and hydrophilic properties to a fiber consisting of a low-melting thermoplastic resin. The present invention also relates to a fabric or formed articles produced from such a highly smooth fiber.
2. Description of the Related Art
In various fields represented by the hygienic material field, there are used woven and non-woven fabrics produced from thermoplastic resins such as polyolefins, polyesters and polyamides. These resins are uniformly dispersed using wet or dry processes, and subsequently adhered with hot air, compressed with hot rolls, and knitted or weaved using high-pressure water flow or metal needles.
However, since fibers made of thermoplastic resins such as polyolefins produce much fiber--fiber and fiber-metal friction in the dry carding process, static electricity is generated and twining occurs.
Because of the present discreteness and improved quality and performance of products, functional thermoplastic resins are often used. In some of these applications, there are used fibers which produce more fiber--fiber and fiber-metal friction than do conventional fibers. Such fibers include resins suitable for low-temperature processing and those having high tackiness. Also, for improving processing efficiencies, increase in processing speed is attempted.
For these reasons, various fiber finishing agents have been proposed for imparting anti-static properties or smoothness to the fibers. Widely used fiber finishing agents include waxes, fatty acid-based fats and oils, and quaternary ammonium salts containing long-chain alkyl groups. However, none of these agents impart sufficient smoothness to the fibers.
On the other hand, silicone-based finishing agents are well known to impart high smoothness to the fibers. For example, emulsion-polymerized dimethyl siloxane and amine-modified silicone have been proposed (Japanese Patent Application Publication NO 48-1480). However, both emulsion-polymerized dimethyl siloxane and amine-modified silicone have poor anti-static properties, interfere with the hydrophilic properties of the fiber, and cause the non-woven fabrics to turn yellow.
For imparting hydrophilic properties to fibers, treatment with polyether-modified silicone has been proposed (e.g., Japanese Patent Application Laid-open Nos. 63-303184, 1-148879 and 2-169774). However, polyether-modified silicone imparts hydrophilic properties but does not impart smoothness to fibers. Therefore, highly smooth fibers provided with higher smoothness, anti-static properties, and hydrophilic properties have still been demanded.